Finance!!!!!!!!!!!!

Using an example of an existing company going public like Martha Stewart, why would Martha Stewart let her company go public give up "control" of the company she founded? I know having a company go public gives them plenty of capital to reinvest in the company, but why would she give up the ultimate control of the company she built? What happens to a company that is so dependent on a "brand person" like Martha Stewart or has the company been transformed beyond just being "her" anymore?